This invention generally relates to intravascular catheters for treating a portion of a body lumen with radiation and particularly to an intravascular catheter and guide wire suitable for delivering a radiation source to the body lumen which utilizes a detachable tip to facilitate re-sterilization of the radiation tip to allow for re-use of the radiation source.
In percutaneous transluminal coronary angioplasty (PCTA) procedures, a guiding catheter having a preshaped distal tip is percutaneously introduced into the cardiovascular system of a patient through the brachial or femoral artery and is advanced therein until the preshaped distal tip is disposed within the aorta adjacent to the ostium of the desired coronary artery. The guiding catheter is then twisted and torqued from its proximal end to turn its distal tip so that it can be guided into the coronary ostium. In an over-the-wire dilatation catheter system, a guide wire and a dilatation catheter having an inflatable balloon on the distal end thereof are introduced into, and advanced through, the proximal end of the guiding catheter to the distal tip of the guiding catheter seated within the coronary ostium. The distal tip of the guide wire is usually manually shaped (i.e., curved) by the physician or one of the attendants before it and the dilatation catheter are introduced into the guiding catheter. The guide wire is usually first advanced out of the distal end of the guiding catheter and is maneuvered into the patient""s coronary vasculature containing the stenosis to be dilated, and is then advanced beyond the stenosis. Thereafter, the dilatation catheter is advanced over the guide wire until the dilatation balloon is positioned across the stenosis. Once the dilatation catheter is in position, the balloon of the catheter is filled with inflation fluid at relatively high pressures (e.g., generally about 4-10 atmospheres) to inflate it to a predetermined size (preferably the same as the normal inner diameter of the artery at that particular location) in order to radially expand the lumen at the stenosis, thereby increasing the effective diameter of the occluded artery. The balloon can then be deflated so that the catheter can be removed and blood flow resumed through the dilated artery.
One common problem that sometimes occurs after an angioplasty procedure has been performed is the development of restenosis at, or near, the original site of the stenosis. When restenosis occurs, a second angioplasty procedure or even bypass surgery may be required, depending upon the degree of restenosis. In order to prevent the need to perform bypass surgery or subsequent angioplasty procedures, various devices and procedures have been developed for reducing the likelihood of development of restenosis after arterial intervention. For example, an expandable tube (commonly termed xe2x80x9cstentxe2x80x9d) designed for permanent implantation within the body lumen has been utilized to help prevent restenosis. By way of example, several stent devices and methods can be found in commonly assigned and commonly owned U.S. Pat. No. 5,158,548 (Lau et al.); U.S. Pat. No. 5,242,399 (Lau et al.); U.S. Pat. No. 5,344,426 (Lau et al.); U.S. Pat. No. 5,421,955 (Lau et al.); U.S. Pat. No. 5,514,154 (Lau et al.); and U.S. Pat. No. 5,360,401 (Turnlund et al.), which are incorporated in their entirety herein.
More recent devices and procedures for preventing restenosis after arterial intervention employ the use of a radiation source to minimize or eliminate proliferation of cells which is thought to be a major factor in the restenotic process. Balloon catheters have been suggested as a means to deliver and maintain the radiation source in the area where arterial intervention has taken place, exposing the area to a sufficient radiation dose to abate cell proliferation. One such device and method are described in International Publication WO 95/19807 (Weinberger). Other devices and methods which utilize radiation treatment delivered by an intravascular catheter are disclosed in commonly-owned and assigned co-pending U.S. Ser. No. 08/654,698, filed May 29, 1996, entitled Radiation-Emitting Flow-Through Temporary Stent, which is incorporated herein by reference. Another medical device for the treatment of a body lumen by radiation is disclosed in European Pat. Ap. 0 688 580 A1 (Schneider).
Up to now, the radiation source has typically been in the form of a radioactive tipped source wire. Presently, such source wires are typically formed by permanently attaching a radiation source to the distal end of a wire. Typically, the radiation source is a solid structure having little or no longitudinal flexibility. This lack of flexibility may increase the difficulty of guiding the distal end of the source wire through small diameter and tortuous body lumens, requiring more effort and time to properly locate the radiation source adjacent an area of restenosis for treatment.
Additionally, presently available radioactive source wires cannot be sterilized for a variety of technical reasons, primarily issues associated with handling a long radioactive component. Thus, contact by the source wire with the patients blood stream had to be avoided to prevent contamination and possible resultant infection. Accordingly, radioactive source wires have been introduced into a patients coronary arteries using catheters such as the Schneider device, which includes a lumen that extends from a proximal opening to an area near the distal end of the catheter, where it xe2x80x9cdead ends.xe2x80x9d This lumen, known as a xe2x80x9cblindxe2x80x9d or xe2x80x9cdead endxe2x80x9d lumen, is intended to carry the radioactive tipped source wire that slides into the lumen once the catheter is in place in the artery or body lumen. When the source wire is positioned, the radioactive section at the distal tip lies near the dead end to provide radiation to the body lumen. The inclusion of a xe2x80x9cblindxe2x80x9d lumen, however, increases the diameter of the catheter, adds complexity to the catheter, and increases the cost to manufacture the catheter.
What has been needed and heretofore unavailable in catheters which provide treatment of the body lumen with a radiation source is an intravascular catheter which utilizes sterile radiation source wires inserted through a lumen open to the blood stream. These source wires would include a removable tip incorporating a radiation source and a flexible, steerable distal end portion. The flexible, removable radiation source tip would be mounted on either a re-sterilizable or disposable core member. Such an intravascular catheter would avoid the requirement of a separate, closed lumen and thus could be manufactured with lower profiles than currently available catheters having xe2x80x9cblindxe2x80x9d lumens. Such an intravascular catheter would have to be easy and inexpensive to manufacture. Additionally, the core member and source wire dispenser should be re-sterilizable or disposable and the detachable tip including that radiation source should be able to be sterilized numerous times, so as to afford multiple use. The present invention fulfills these and other needs.
The invention provides a radiation source wire using a detachable tip and radiation source which allows the introduction of a sterilizable and re-usable radioactive tipped source wire to treat a vascular location of interest in a patient, such as where a vessel has become re-stenosed subsequent to a prior intravascular procedure.
In accordance with the present invention, the source wire includes a detachable tip including a radiation source that may be detached from a core member to be resterilized. The core member, including a source wire dispenser mounted on a remote afterloader, may be resterilized or disposable.
In another aspect of the invention, the detachable tip includes a flexible portion to improve the maneuverability of the radioactive source wire as it is guided through the body lumen. This flexible portion allows the radioactive source to be positioned to treat an area of restenosis in less time and with less difficulty than presently available source wires.
Other features and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the features of the invention.